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FUNCTION:PNG2BMP SOURCE CODE:main.c LIBRARY USE:libpng RUNNING:p2b ///////////////////////////////////////// 0.api: int png2bmp(char *pngname,char *bmpname)

input parameters: pngname:name of input png file.eg:*pngname="test.png" bmpname:name of output bmp file.eg:*bmpname="test.bmp"

output parameters: return Error Code(see more in No.7) /////////////////////////////////////////

1.function:translate png image(test.png) to bmp file(test.bmp) 2.input:test.png 3.output:test.bmp 4.function: (if not listed,see libjpeg document for more information) void read_png_info() :read info from pngfile to [read_ptr,read_info_ptr](defination according to libpng document) void write_bmp_data() :wirte imagedata from read_ptr to buffer(pSrc),write bmpfile data to pDst according to colortype,should used after read_png_info()

5.colortype: (according to png file format,see png format for more) 2:pSrc is in RGB_24,fill pDst(A level:0xff) 3:pSrc is in palette,fill pDst by palette 6:pSrc is in ARGB_32,fill pDst as pSrc other colortype do not support

6.static vars: png_FILE_p fpin; :libpng-pointer of input png file FILE *fpout; :pointer of output bmp file png_structp read_ptr; :libpng-stream,with png file data in it,used by libpng png_infop read_info_ptr, end_info_ptr; :libpng-stream,with png_file_info/png_file_end in it,used by libpng png_structp write_ptr; :libpng-stream,for write png file data,used by libpng(useless) png_infop write_info_ptr,write_end_info_ptr; :libpng-stream,for write png_file_info/png_file_end,used by libpng(useless) png_bytep row_buf; :unused buffer; : int num_pass, pass; :unused int,for decode interlanced png data png_uint_32 width, height; :image's width/height(px) int bit_depth, color_type; :image's bit_depth/color_type(see colortype in No.5) int interlace_type, compression_type, filter_type; :image's interlace_type/compression_type/filter_type,see png format for more int isRGB; :is png a rgb file png_textp text_ptr; :libpng-stream,with png's text data in it,used by libpng int num_text; :num of png's text data png_timep mod_time; :libpng-stream,with png's time data in it,used by libpng png_colorp palette; :libpng-colormap,used by libpng
int num_palette; :num of png file's palette

7.Error Code PASS :pass ERROR_PNGREAD :cannot open or read from png file ERROR_BMPWRITE :cannot open or write into bmp file ERROR_COLORTYPE :unknown colortype occurred,may be png file damage

see libpng document in http://www.libpng.org/pub/png/libpng-manual.txt